The DNG generated by CHDK on a Canon A550 has no embedded preview

I have recently bought a used Canon A550 and tried using CHDK with it. I firstly wanted to use it as a time-lapse camera, so I installed the Ultra Intervalometer on the camera and enabled RAW file support.

All went well, however, the DNG files that come out of the camera have no embedded preview. For example: I can not use my Mac's Quicklook or Preview on the files to check the contents.The embedded preview is also necessary to preview a time-lapse in LRtimelapse.The files do have small thumbnails though.

I need to import the DNG files into Lightroom and update the DNG preview & metadata (this function is found in the Metadata menu when in Library mode) to get the previews right. For several hundred DNG files this process takes a while as Lightroom takes around 2-3 seconds to process each image. Is there a way to command CHDK to generate these previews when writing the DNG to the card?Or is there some method to embed the JPEG that is written simultaneously with the DNG file?

I have recently bought a used Canon A550 and tried using CHDK with it. I firstly wanted to use it as a time-lapse camera, so I installed the Ultra Intervalometer on the camera and enabled RAW file support.

All went well, however, the DNG files that come out of the camera have no embedded preview. For example: I can not use my Mac's Quicklook or Preview on the files to check the contents.The embedded preview is also necessary to preview a time-lapse in LRtimelapse.The files do have small thumbnails though.

I need to import the DNG files into Lightroom and update the DNG preview & metadata (this function is found in the Metadata menu when in Library mode) to get the previews right. For several hundred DNG files this process takes a while as Lightroom takes around 2-3 seconds to process each image. Is there a way to command CHDK to generate these previews when writing the DNG to the card?Or is there some method to embed the JPEG that is written simultaneously with the DNG file?

Technically it's possible; but the DNG is created before the camera has created the JPEG image so that is not available for use.

It would be a lot of work, and would slow down the DNG creation - possibly by a large margin.

This is something that is better done on you PC - you can use the Adobe DNG Convertor program to batch convert a directory of CHDK DNG files.